btsem.c

/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 4 -*- *//* ***** BEGIN LICENSE BLOCK ***** * Version: MPL 1.1/GPL 2.0/LGPL 2.1 * * The contents of this file are subject to the Mozilla Public License Version * 1.1 (the "License"); you may not use this file except in compliance with * the License. You may obtain a copy of the License at * http://www.mozilla.org/MPL/ * * Software distributed under the License is distributed on an "AS IS" basis, * WITHOUT WARRANTY OF ANY KIND, either express or implied. See the License * for the specific language governing rights and limitations under the * License. * * The Original Code is the Netscape Portable Runtime (NSPR). * * The Initial Developer of the Original Code is * Netscape Communications Corporation. * Portions created by the Initial Developer are Copyright (C) 1998-2000 * the Initial Developer. All Rights Reserved. * * Contributor(s): * * Alternatively, the contents of this file may be used under the terms of * either the GNU General Public License Version 2 or later (the "GPL"), or * the GNU Lesser General Public License Version 2.1 or later (the "LGPL"), * in which case the provisions of the GPL or the LGPL are applicable instead * of those above. If you wish to allow use of your version of this file only * under the terms of either the GPL or the LGPL, and not to allow others to * use your version of this file under the terms of the MPL, indicate your * decision by deleting the provisions above and replace them with the notice * and other provisions required by the GPL or the LGPL. If you do not delete * the provisions above, a recipient may use your version of this file under * the terms of any one of the MPL, the GPL or the LGPL. * * ***** END LICENSE BLOCK ***** */#include <kernel/OS.h>#include "primpl.h"/*** Create a new semaphore object.*/
PR_IMPLEMENT(PRSemaphore*)
PR_NewSem (PRUintn value)
{
PRSemaphore *semaphore;
if (!_pr_initialized) _PR_ImplicitInitialization();
semaphore = PR_NEWZAP(PRSemaphore);
if (NULL != semaphore) {
if ((semaphore->sem = create_sem(value, "nspr_sem")) < B_NO_ERROR)
returnNULL;
elsereturn semaphore;
}
returnNULL;
}
/*** Destroy the given semaphore object.***/
PR_IMPLEMENT(void)
PR_DestroySem (PRSemaphore *sem)
{
status_t result;
PR_ASSERT(sem != NULL);
result = delete_sem(sem->sem);
PR_ASSERT(result == B_NO_ERROR);
PR_DELETE(sem);
}
/*** Wait on a Semaphore.** ** This routine allows a calling thread to wait or proceed depending upon** the state of the semahore sem. The thread can proceed only if the** counter value of the semaphore sem is currently greater than 0. If the** value of semaphore sem is positive, it is decremented by one and the** routine returns immediately allowing the calling thread to continue. If** the value of semaphore sem is 0, the calling thread blocks awaiting the** semaphore to be released by another thread.** ** This routine can return PR_PENDING_INTERRUPT if the waiting thread ** has been interrupted.*/
PR_IMPLEMENT(PRStatus)
PR_WaitSem (PRSemaphore *sem)
{
PR_ASSERT(sem != NULL);
if (acquire_sem(sem->sem) == B_NO_ERROR)
return PR_SUCCESS;
elsereturn PR_FAILURE;
}
/*** This routine increments the counter value of the semaphore. If other** threads are blocked for the semaphore, then the scheduler will** determine which ONE thread will be unblocked.*/
PR_IMPLEMENT(void)
PR_PostSem (PRSemaphore *sem)
{
status_t result;
PR_ASSERT(sem != NULL);
result = release_sem(sem->sem);
PR_ASSERT(result == B_NO_ERROR);
}
/*** Returns the value of the semaphore referenced by sem without affecting** the state of the semaphore. The value represents the semaphore value** at the time of the call, but may not be the actual value when the** caller inspects it.*/
PR_IMPLEMENT(PRUintn)
PR_GetValueSem (PRSemaphore *sem)
{
sem_info info;
PR_ASSERT(sem != NULL);
get_sem_info(sem->sem, &info);
return info.count;
}